Adaptações morfofisiológicas de Cichla kelberi Kullander & Ferreira, 2006 (Cichliformes: Cichlidae) em diferentes estágios reprodutivos

Abstract

The yellow peacock bass (Ciclha kelberi) has been introduced into reservoirs in Brazil, and information on its energetic, reproductive, gonadal maturation, and lipid profile is still scarce, especially in the state of Maranhão. Such studies are limited and restricted to lake regions. Therefore, this study aims to evaluate the morphophysiological, energetic, and cellular adaptations of C. kelberi at different reproductive stages in the Lençóis Maranhenses National Park, Barreirinhas, Maranhão. Seventy-six specimens were collected: 30 females and 46 males. The captured specimens were weighed and their livers, stomachs, and gonads were removed for biometric and histological analysis. The dorsal muscle, liver, and venter were also removed to determine tissue lipid concentrations. In the microscopic evaluation of the gonads, the following stages were observed: maturing (44.7%), mature (28.9%), and emptied (26.3%). Females predominated in the emptied stage and males in the maturing stage. In females, cells were visible in all stages of oocyte development. The sex ratio for sampling was 1.5 males to 1 female. The highest frequency of individuals was in lengths between 31.0 and 41.0 cm (49.9%), males were larger, with a significant difference between the sexes (p = 0.01). Females obtained positive allometry (b = 3.1) and males negative (b = 2.9). The condition factor and the gonadosomatic index of the species showed elevations in the mature gonadal development stage, indicating well-being and reproductive fitness. The hepatosomatic index (HSI) of males (0.7) was higher than that of females (0.5). Males showed an increase as gonadal maturation progressed, while females showed a decline in the mature stage. Lipid analysis demonstrated that the venterchae is where the highest concentration is found (7.6%). Females presented greater lipid fluctuations in the tissues and organs studied, while in males, the fluctuations were discreet and the percentages were more constant. The coefficient of determination showed that 45% of stomach weights were influenced by fish weight. The stomach condition factor and weight were lower in females than in males. The species efficiently converts environmental resources into energy for maintaining its ecology and reproduction. More detailed studies on the ecology and mechanisms that influence the adaptive and reproductive success of the species are needed to implement effective management measures.